The present invention relates to apparatus for sealing the foldable flaps of cartons of random sizes by applying a self-adhesive tape material along the edges of the flaps, and more particularly to improved assemblies for automatically infolding the top flaps prior to the application of the adhesvie material and for controlling the positioning of the flap folding assembly at or above the upper edge of the carton.
In the packaging industry, corrugated and fiberboard cartons have been used for many years and various machines have been developed which are capable of sealing such cartons either by gluing the flaps, taping the flaps, or by stapling or otherwise providing mechanical fasteners to maintain the flaps in a closed position. Many of these machines are designed to accept cartons of random width and height by providing various types of sensing means to control the transverse movement of the side arms associated therewith and the vertical movement of the top sealing head assembly. Examples of such machines are disclosed in U.S. Pat. Nos. 4,079,577 and 4,364,219, both of which have the same assignee as the present invention.
Although many of the heretofore known machines have operated quite satisfactorily under most operating conditions, in certain instances they have had difficulties in handling some of the cartons which have been fed thereinto for sealing. For example, the flap folding mechanisms of such machines have experienced difficulties in infolding a trailing top minor flap which is substantially beyond a vertical orientation. Various types of pivotally mounted kickers have been utilized to alleviate this problem, however, they have not totally solved the problem. Examples of such kickers are disclosed in U.S. Pat. Nos. 3,267,640 and 3,973,375. Another problem frequently encountered by heretofore known machines is the tendency to crush the end walls of cartons which are not completely filled, due to the forces applied by the sealing head assembly or flap folding assembly as it is lowered thereon during operation. In order to alleviate this problem it is necessary to accurately sense the top of the end walls and positively retain the sealing head assembly immediately thereabove without the application of crushing forces. It is also important that the machine operate rapidly to increase the utilization of the machine.